Greenhouse Gas Emissions | Definition, CO2 & Climate Change
Greenhouse gas emissions are at the forefront of climate change discussions. They play a crucial role in our planet’s future as they are majorly responsible for temperature variations on Earth and subsequent climate change.
In this blog, we discuss a lot about this topic. We begin with the definition of greenhouse gases (GHGs), focusing majorly on carbon dioxide (CO2) and its impact on global warming. We then move on to exploring the greenhouse effect, examining how these GHGs trap heat in Earth’s atmosphere and contribute to rising temperatures.
Subsequently, we discuss the various sources of greenhouse gas emissions, their far-reaching consequences on ecosystems and human society, and effective strategies to reduce our carbon footprint to mitigate climate change. Let’s begin!
What Are Greenhouse Gases?
Now, let’s begin with the basics. Let us first understand what greenhouse gases exactly are and what role do they play in the earth’s atmosphere.
The Basics
Greenhouse gases are atmospheric gases that trap heat from the Sun within Earth’s atmosphere. They are like Earth’s thermal blanket. They let sunlight in but keep some of the heat from escaping back into space through something called the “greenhouse effect”. This greenhouse effect keeps our planet warm and cosy enough for life.
The primary greenhouse gases include Carbon dioxide (CO2), Methane (CH4), Water vapour (H2O), Nitrous oxide (N2O), Ozone (O3), Chlorofluorocarbons (CFCs) and Hydrofluorocarbons (HFCs). CO2 is the most significant greenhouse gas due to its abundance and long atmospheric lifetime. Methane, though less abundant, has a much higher heat-trapping capacity. Water vapour is the most abundant greenhouse gas but is not directly influenced by human activities.
The others, while present in smaller quantities, can have potent warming effects. Below we look at the lifetime and global warming potential of these gases, which highlights the lasting impact that these can have on our atmosphere.
Table 1. Major Greenhouse Gases Associated with Anthropogenic Activities
| Greenhouse Gas | Sources | Average Lifetime in Atmosphere | 100-year Global Warming Potential (GWP) |
|---|---|---|---|
| Carbon Dioxide (CO2) | Fossil fuels, deforestation | Its lifetime cannot be represented with a single value because CO2 is not destroyed over time, but instead moves among different parts of the ocean–atmosphere–land system. | 1 |
| Methane (CH4) | Agriculture, waste, fossil fuels | 11.8 years | 27.0–29.8 |
| Nitrous Oxide (N2O) | Agriculture, industrial activities | 109 years | 273 |
| Fluorinated Gases | Industrial, commercial and household processes. They do not occur naturally. | A few weeks to thousands of years | Up to 25,200 |
Source: Climate Change Indicators: Greenhouse Gases, U.S. EPA
Human activities, particularly fossil fuel combustion and deforestation, have significantly increased greenhouse gas concentrations in the atmosphere. Human activities have ramped up their levels, driving climate change since the mid-20th century (EPA).
The Heat Trap
Greenhouse gases absorb the heat that the Earth emits after being warmed by the sun. Instead of letting the heat escape into space, GHGs send it back down to Earth. This keeps our planet warm but can cause overheating when the levels of these GHGs rise.
- Carbon Dioxide (CO2): The main culprit from human activities. It sticks around in the atmosphere for a long time, sometimes thousands of years (EPA).
- Methane (CH4): Has a larger warming potential than CO2 in trapping heat but doesn’t last as long in the atmosphere.
- Nitrous Oxide (N2O): Comes from farming and industry, with a much higher warming potential than CO2.
- Fluorinated Gases: Man-made and used in industry, these gases have a super high warming potential and can linger for ages.
Presently, CO2 levels have shot up by ~50% above pre-industrial times (before 1750), making it the top contributor to global warming effects. It is high time that we the human race get a grip on greenhouse gases and control their impact on the environment if we want to live on this earth for the coming centuries.
Main Sources of Greenhouse Gas Emissions
Greenhouse gas emissions come mainly from various human activities. The main sources are:
1. Burning of Fossil Fuels
Burning fossil fuels like coal, oil, and natural gas has been the biggest driver of greenhouse gases over the last decades. We use these fuels to generate electricity, heat our homes, and power our cars, which releases a ton of carbon dioxide (CO₂) and other harmful gases. Table 2 below shows the share of different anthropogenic activities in GHG emissions.
Table 2. Share of different anthropogenic activities in GHG emissions
| Activity | Percentage of Total Emissions |
|---|---|
| Electricity and Heat Production | ~31% |
| Manufacturing, Industrial Processes and Construction | ~19% |
| Transportation | ~15% |
Source: Global Emissions, C2ES
Globally, electricity and heat production is responsible for a lion’s share of the GHG emissions. In the U.S., transportation tops the list making up 29% of total emissions in 2022 (EPA). This includes everything from cars and trucks to planes, trains, and ships. Light-duty trucks are the biggest offenders here.
2. Industrial Emissions
The industrial sector accounted for around 6% of global greenhouse gas emissions and about 23% of U.S. greenhouse gas emissions (C2ES, EPA). This includes emissions from manufacturing, mining, and construction. While direct emissions have dropped by nearly 10% since 1990, the sector’s overall impact is bigger when you consider indirect emissions from electricity use.
3. Agricultural Emissions
Agriculture is responsible for about 11% of global greenhouse gas emissions and 9% of U.S. greenhouse gas emissions (C2ES, EPA). The main sources are livestock, manure management, rice production, soil management, and the burning of agricultural residues. Since 1990, emissions from livestock manure management have shot up by 54%.
GHGs have a major impact leading to climate change. Understanding these main sources of greenhouse gas emissions is key to fighting climate change.
Impact on Climate
Though needed to maintain habitable conditions on the earth, excess Greenhouse gas emissions due to various reasons are messing with the earth and causing climate change. Let’s understand how these emissions are impacting the earth.
1. Global Warming
Global warming is the long-term rise in Earth’s average temperature. Human activities, especially burning fossil fuels, have increased levels of greenhouse gases in the air. According to the EPA, these gases are the main reason behind climate change since the mid-20th century.
The decade from 2011 to 2020 was the hottest on record. In 2017, global temperatures crossed 1.0°C above pre-industrial levels. The Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) released in 2023 concluded that “Human influence is unequivocally causing climate change. Global warming of 1.5°C and 2°C will be exceeded during this century unless there are immediate, rapid, and large-scale reductions in greenhouse gas emissions”.
This is scary because a 2°C increase could spell disaster for both the environment and our health. If the current pace of warming continues, global temperature could increase by ~1.5°C around 2040 (IPCC).
Table 3. Temperature increase due to GHG emissions
| Year | Temperature Increase (°C) |
|---|---|
| 2000 | ~0.75 |
| 2015 | ~0.87 |
| 2017 | ~1.0 |
| 2040 (anticipated) | ~1.5 |
Source: FAQ Chapter 1, IPCC
Human-caused global warming is rising by about 0.2°C per decade. This makes it urgent to cut greenhouse gas emissions (IPCC).
2. Extreme Weather
As the planet heats up, we see more impact on the weather such as increased heatwaves, heavy rain, hurricanes, and droughts. These events are getting more frequent and intense because of the extra energy in the climate system from higher greenhouse gas levels.
Table 4. Weather events in the past decades
| Weather Event | Example | Impact |
|---|---|---|
| Heatwaves | Europe 2003 | at least 30,000 deaths |
| Heavy Rainfall | US Midwest 2019 | Flooding huge areas of farmland and cities |
| Hurricanes | Hurricane Maria 2017 | Damaged the roofs of as much as 98% of the island’s buildings |
| Droughts | California 2012-2016 | At least 2,600 well-dependent households experienced water shortages and roughly 150 small water systems needed emergency assistance |
Source: Secondary Research
For more on how extreme weather impacts greenhouse gases, check out our articles on extreme weather events.
3. Rising Sea Levels
Rising sea levels are another big problem of global warming. The ocean levels are rising because of thermal expansion and melting ice caps. This rise threatens coastal areas, ecosystems, and infrastructure.
Table 5. Global average absolute sea level rise over the past decades
| Year | Sea Level Rise Compared to 1880 (inches) |
|---|---|
| 2000 | ~7.1 |
| 2010 | ~8.2 |
| 2020 | ~9.7 |
Source: Climate Change Indicators: Sea Level, U.S. EPA
Higher sea levels can cause more flooding, and erosion, and force people to move, often called climate refugees. It’s crucial to tackle greenhouse gas emissions to slow this down and protect vulnerable areas.
Greenhouse gas emissions drive global warming, extreme weather, and rising sea levels. Explore our sections on renewable energy solutions and climate change policy to learn more about how to fight these effects.
Health and Environment
Climate change caused by greenhouse gas emissions not only impacts the environment but also poses health risks for the population and damages our ecosystems. Let’s see how.
1. Health Risks
Health risks might not be the first thing that pops into your head when you think about greenhouse gas emissions. In reality, however, there are multiple health risks associated with climate change. The EPA points out that healthcare is affected by climate change caused by greenhouse gases. This double whammy affects both our planet and our well-being.
Higher temperatures increase the risk of heat-related illnesses and deaths. Heatwaves can lead to heat exhaustion and heatstroke. Plus, warmer weather can mess with air quality by boosting ground-level ozone, a major part of smog. Bad air quality can pose health risks like heart and lung diseases.
Table 6. Health risks related to Greenhouse Gas emissions
| Health Risk | Cause | Impact |
|---|---|---|
| Heat-Related Illnesses | Heatwaves | Heat exhaustion, heatstroke |
| Respiratory Issues | Poor air quality, smog | Asthma, bronchitis |
| Vector-Borne Diseases | Warmer temperatures | More diseases like malaria and dengue |
Source: Climate Change Impacts on Health, U.S. EPA
Cutting greenhouse gas emissions from healthcare facilities could save lives and reduce healthcare costs. Want to know more? Check out our page on climate change and health.
2. Ecosystem Damage
Greenhouse gas emissions also wreak havoc on our ecosystems. In 2015, a legally binding international treaty on climate change called the Paris Agreement was adopted by 196 Parties at the UN Climate Change Conference (COP21) in Paris, France. The agreement aims to limit the increase in the global average temperature to well below 2°C above pre-industrial (pre-1750) levels and pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels. A 2°C rise in temperature compared to pre-industrial levels could spell big environmental trouble (European Commission).
This is because rising temperatures and shifting rainfall patterns can throw ecosystems out of place leading to loss of biodiversity. For example, coral reefs are super sensitive to temperature changes and can suffer bleaching events, making them more vulnerable to disease.
Table 7. Ecosystem impact and its consequences
| Ecosystem Impact | Cause | Consequence |
|---|---|---|
| Coral Bleaching | Rising sea temperatures | Coral death, loss of marine life |
| Deforestation | Climate changes | Loss of habitat, reduced biodiversity |
| Ocean Acidification | Increased CO2 levels | Harm to marine life, disrupted food chains |
Source: Secondary Research
As per the IPCC, human activities have been the main driver of climate change. The 2023 Sixth Assessment Report of the IPCC concluded that “Global warming of 1.5°C and 2°C will be exceeded during this century unless there are immediate, rapid, and large-scale reductions in greenhouse gas emissions”.
This is an alarming situation. To save our ecosystems, we need to tackle these emissions head-on. Cutting down on greenhouse gas emissions can reduce health risks and protect our ecosystems.
For more on how climate change affects specific ecosystems, check out our articles on ocean biodiversity and the impact of deforestation.
Cutting Down Emissions
Cutting down greenhouse gases is key to tackling climate change. There is an urgent need to act. The following measures can help limit Greenhouse Gas emissions and subsequent climate change.
1. Enhanced Energy Efficiency
Boosting energy efficiency is a major lever to reduce greenhouse gases. The U.S. EPA’s ENERGY STAR Program teams up with over 15,000 organizations to push energy-saving solutions that cut emissions (EPA). Here’s what you can do to contribute your part to this:
- Swap out old appliances for ENERGY STAR-certified ones.
- Use LED bulbs instead of old-school incandescent ones.
- Get a programmable thermostat to fine-tune your heating and cooling.
- Seal and insulate your home to keep the energy in.
Table 8. Potential savings from energy-efficient equipment
| Action | Potential Savings |
|---|---|
| LED Bulbs | Up to 75% less energy |
| Programmable Thermostats | Up to 10% savings on heating/cooling |
| Home Insulation | Up to 10% savings on total energy costs |
Source: U.S. Department of Energy
2. Renewable Energy Adoption
Switching to renewable energy is another powerful lever for reducing GHG emissions. The U.S. EPA’s Green Power Partnership has over 780 partners using billions of kilowatt-hours of green power every year. You can also do your bit to adopt renewable energy in your life:
- Install solar panels on your roof.
- Pick a green energy provider.
- Support wind, solar, and hydroelectric projects.
If you want to learn more about renewable energy, check out our articles on renewable energy solutions.
3. Sustainable Transportation
As per the United Nations, the transport sector is responsible for about 25% of global greenhouse gas emissions. It is, therefore, imperative that by choosing greener ways to get around, you can cut your carbon footprint. Here are some ideas that you can adopt:
- Use public transportation.
- Bike or walk for short trips.
- Drive an electric or hybrid car.
- Carpool with friends or coworkers.
Table 9. Transportation method and emission savings
| Transportation method | CO2 emission savings per passenger kilometre (compared to petrol cars) |
|---|---|
| Public Train | 70-80% less |
| Electric Vehicles | 60-70% less |
| Bike/Walking | 100% emission-free |
Source: Which form of transport has the smallest carbon footprint?, Our World in Data
If you want to learn more about sustainable transportation, visit our articles on green mobility.
These habits can help you cut greenhouse gases and fight climate change. Find more resources and ideas in our sections on individual climate action and climate change education.
Personal Actions
Now let us move to the most interesting part of this article. What we can do make a real impact in reducing greenhouse gas emissions? Here we discuss some practical tips on how to make a difference through your daily habits, food choices, and waste reduction. Let’s begin!
1. Daily Habits
Small tweaks in your daily routine can have a big impact on the environment. Here are some habits that you can adopt:
- Energy Efficiency: Make it a habit to turn off lights when you leave a room and use energy-efficient appliances. The EPA’s ENERGY STAR Program has great tools and info to help you save energy.
- Transportation Choices: Instead of driving, prefer walking or using public transportation. These alternatives cut down on transportation emissions, which make up about a quarter of the global greenhouse gas emissions. Check out our section on eco-friendly travel for more ideas.
- Water Conservation: Fix leaks and take shorter showers whenever possible. This habit can save a lot of water and the energy used to pump, heat, and treat water.
If we all adopt these simple habits and repeat them daily, together we all can have a significant positive impact on the environment around us.
2. Food Choices
What you eat matters more than you think. Eating more sustainably can have a lasting impact. Here are some choices that you can adopt:
- Plant-Based Diet: Going plant-based can make a huge difference. Livestock farming contributes to about 20% of global carbon emissions. A plant-based diet could prevent 65 gigatons of carbon dioxide from entering the atmosphere by 2050.
- Local and Seasonal Foods: Eating locally grown and seasonal foods cuts down on the carbon footprint from transportation and storage.
- Reducing Food Waste: Planning meals and storing food properly helps minimize waste. This can help you optimise food production and can have a lasting impact on your entire food supply chain. If you want more tips, you can check our section on waste management.
Table 10. Food choices and their impact on the environment
| Food Choice | Impact on Emissions |
|---|---|
| Plant-Based Diet | Can prevent 65 gigatons of CO2 by 2050 |
| Livestock Farming | Contributes to 20% of global carbon emissions |
| Local Foods | Reduces transportation emissions |
Source: Secondary Research
3. Waste Reduction
Cutting down on waste is another great way to lower greenhouse gas emissions. Here’s what you can do:
- Recycling and Composting: Recycling and composting reduce the amount of waste that ends up in landfills, which are big sources of methane emissions. Reducing waste by recycling can limit waste that reaches landfills and subsequently reduce emissions of methane, which is a greenhouse gas.
- Reusable Items: Use reusable bags, bottles, and containers to cut down on single-use plastics.
- Minimalism: Buying only what you need and choosing products with minimal packaging reduces waste. For more on this, check out our section on minimalist living.
These simple habits, food choices, and waste-reduction strategies can go a long way in the fight against climate change. For more detailed actions, explore our pages on climate change & pollution.
Community Efforts
Community efforts are key to cutting down greenhouse gas emissions. When we band together, we can make real changes that help our environment and our health. Communities can work together and make the following efforts to limit greenhouse gas emissions.
1. Local Projects
Local projects are a fantastic way for communities to tackle greenhouse gas emissions. One effective method that your community can adopt is joining programs like the U.S. EPA’s Green Power Partnership. This program has over 780 partners using billions of kilowatt-hours of green power each year. These programs cut environmental impacts by pushing for renewable energy sources.
Communities can also consider energy efficiency projects. For instance, the U.S. EPA’s ENERGY STAR Program teams up with over 15,000 organizations to offer tools and info that promote energy-efficient solutions. This helps slash energy use and greenhouse gas emissions.
2. Green Spaces
Creating and keeping green spaces in communities is another powerful way to fight climate change. Green spaces like parks, community gardens, and urban forests soak up carbon dioxide, a major greenhouse gas. They also provide homes for wildlife and clean the air.
Your community can limit the impact by creating more green spaces for promoting carbon sequestration, which captures and stores atmospheric carbon dioxide. For more on this, check out our article on carbon capture, utilisation and storage.
3. Public Transit
Public transit is a crucial piece of sustainable communities. Transportation makes up about a quarter of global greenhouse gas emissions. Communities can encourage their members to adopt public transit like buses, trains, and subways. This can cut their carbon footprint significantly.
Encouraging public transit also means fewer cars on the road, which reduces traffic and emissions. Plus, alternatives like biking and walking can further lower greenhouse gas emissions and boost public health.
Through local projects, green spaces, and public transit, communities can play a big role in cutting greenhouse gas emissions.
Government Policies
We now reach the last section of the article. Here we discuss how government policies can help reduce greenhouse gas emissions. Cutting down greenhouse gas emissions needs solid government policies. These policies fall into three main buckets: rules, rewards, and global pacts.
1. Rules
Governments set rules to cap emissions from different sectors. Since 2010, the EPA’s Greenhouse Gas Reporting Program has required facilities emitting over 25,000 metric tons of carbon dioxide equivalents per year to report their emissions. This transparency helps keep tabs on and manage emissions better.
Table 11. Programs and their impact
| Program | What It Does | Impact |
|---|---|---|
| Greenhouse Gas Reporting Program | Facilities emitting over 25,000 metric tons of CO2 equivalents must report emissions | Better tracking and management of emissions |
| ENERGY STAR Program | Partners with over 15,000 organizations to promote energy-efficient solutions | Cuts down greenhouse gas emissions |
Source: EPA’s Greenhouse Gas Reporting Program, U.S. EPA’s ENERGY STAR Program
2. Rewards
Rewards allow the necessary space for businesses and users to go green. The EPA’s ENERGY STAR Program teams up with over 15,000 organizations to offer tools and info that promote energy-efficient solutions, helping to slash greenhouse gas emissions (EPA). Plus, the Green Power Partnership has over 780 partners who voluntarily use billions of kilowatt-hours of green power every year.
Table 12. Rewards and its impact
| Program | What It Does | Impact |
|---|---|---|
| ENERGY STAR Program | Promotes energy-efficient solutions | Helps cut emissions |
| Green Power Partnership | Partners voluntarily use green power | Lowers environmental impacts from regular electricity |
Source: U.S. EPA’s ENERGY STAR Program
3. Global Pacts
Global pacts are key in the fight against greenhouse gas emissions. These agreements set targets and frameworks for countries to follow, ensuring a united front against climate change. Take the Paris Agreement, for instance, which aims to keep global warming well below 2°C above pre-industrial levels (European Commission). Such agreements are crucial for tackling the worldwide nature of climate change and fostering cooperation among nations.
Government policies, whether they’re rules, rewards, or global pacts, are essential for cutting greenhouse gas emissions and fighting climate change. These policies can help build a greener future. For more on climate change agreements, visit our section on climate change & pollution.
In Conclusion
The rising concentrations of CO2 and other greenhouse gases are driving global temperature increases, leading to far-reaching consequences for ecosystems, weather patterns, and human societies. Addressing this issue requires a multifaceted approach, including transitioning to renewable energy sources, improving energy efficiency, and implementing sustainable daily habits and community practices.
As individuals and nations, it is important that we urgently take collective action to reduce emissions. Our actions today will shape the future of our planet. The time for decisive action is now and we must strive to mitigate climate change and preserve a habitable Earth for our future generations.
